The Two Truths - The Transcendent Absolute (Nonduality) and Phenomena

1. The Absolute and the Relative Reality

The Nondual Absolute Reality in Itself - Shunyata, Paramatman, Tao, Buddha-nature, etc -
is the Supreme Ground of all Reality. Its attainment is experienced
as Nirvana or Liberation or or Self-Realization. The opposite of
this state is the world of phenomena, Maya, the relative truth, Illusion,
Samsara, "the wheel of rebirth", subject to Ignorance (avidya) of one's
True Nature, craving, unhappiness, and so on.

It is generally considered that between these two extremes
there is no continuum, unlike the other dimension/parameters we have considered.
The lower, relative reality, is a juxtoposition on the higher, the Absolute
Reality. That's why the various Indian philosophies (Vedanta, Mahayana,
etc) speak of the "Two Truths", the Relative and the Absolute Truth.
Hence Enlightenment (realisation of the Absolute) is not something to be
attained, because one always was and is the Absolute. Enlightenment
is simply the realisation that you are the Absolute right now, and that
there is no birth or death, future or past, self or other, but only the
eternal present, the one universal "I" (this is putting it very simply,
but space does not allow an analysis of the subtlties of the doctrine,
or the differences between Mahayana Buddhist and Advaita Vedantin conceptions of Enlightenment).

2. Three Grades of Knowledge

Yet from another point of view one can suggest a continuum,
in the area of Advaitin and Mahayanist epistemology (science of knowledge).
Whereas Western academic epistemology is divided between the Rationalists,
who say we know things because our minds contain pre-existent ideas, and
the Empiricists, who say that the mind is a blank slate, and everything
we know and learn is through the senses, the Indian mystical epistemology
is concerned with spiritual knowledge, rather than knowledge about (general
or mundane) knowledge.

Basically, this monistic philosophy (both Advaita and Mahayana affirm a single Absolute Reality) refers to three grades of knowing,
each lower of which is false in relation to the next.

The lowest grade is illusion,
or hallucination, such as things in a dream, which appear real while dreaming,
but then are seen to be false upon awakening; or tricks of the eye, such
a rope which in the distance or in the dark appears to be a snake, or mother-of-pearl
which appears to be silver.

The next level is "empirical" knowledge;
knowledge as it ap-pears to the senses (and, one may add, to the instruments
of modern science), and which reveals the world as it "objectively" is.

The highest level is transcendental
knowledge; knowledge of Reality as it actually is, revealed through
the superconscious or enlightenment experience. Relative to this
absolute knowledge, everyday empirical knowledge stands in the same relation
as hallucination or misperception stands to the latter. That is,
the objective world itself is realised to be a "dream", an "illusion",
a "rope-snake", or whatever. Realisation of absolute knowledge is
the same as realisation of the Absolute (or Godhead) itself, because in
these spiritual traditions the Absolute is itself considered as a - or
rather the - faculty of knowing or experience; or in other words of the
nature of pure Consciousness.

The terms of the three grades of knowledge vary according
to the particular school of thought. To give three examples

An interesting twist to this is given in Tibetan Buddhism,
where there is the distinction between the lower Enlightenment of the Dharmakaya
(Truth-dimension) and the greater Enlightenment of the Swabhavakaya (Self-nature
dimension). This theme is adapted by Da Free John, who distinguishes
between subjective Enlightenment (realisation of the Self or Absolute Within),
and objective Enlightement (realisation of the Absolute - the Radiant Transcendental
Being - in all things. Hence we could say that the Paramartha or
Absolute Truth is divided into a lesser and a greater.

3. The Way of Form and the Way of Formlessness

All this is explaining things from a pure "Knowledge Yoga" perspective, but there are also other teachings - Tibetan Buddhism and Taoist Yoga to name just two - which strive for realisation of the Absolute through other dimensions of being, such as the Inner or etheric-psychic-occult. It all depends whether one prefers the austere approach or the way of form.

A good example of the way of form is shown by Tibetan Buddhism, in which
painstakingly elaborate visualisation (Mental body), including visualisation of chakras (Etheric body), deities, mandalas, etc, is combined with focused meditation (inner mental being) to contact and identify with particulardeities (expanded/shuddhashuddha being) and activate the subtle "winds"
(vayu = prana = ch'i) (inner etheric body). This finally generates
first an "impure illusory body" (Inner Etheric and Inner Astral; Lower
Paramartha) and finally a "pure illusory body" (Higher Paramartha), which
latter represents the attainment of full Buddhahood.

In contrast to all this is the austere but much
simpler and presumably easier to follow techniques of Advaita
Vedanta, which attempts to realise the Absolute through a continual
intuitive-mental approach of focusing on awareness (see for example the
teachings of Ramana Maharshi). The Rinzai Zen attempt to break down the mental structure through the constant pondering on a paradoxical utteance or koan is somewhat
similiar, although employing a novel approach.